Stuart Lancaster, the caretaker coach charged with guiding a chastened England through the forthcoming Six Nations in a style that will consign last year's malodorous World Cup campaign to the septic tank of history, may not be granted a complete run of tournament games in which to stake his claim for the full-time role. Senior Rugby Football Union figures said yesterday that an appointment could be made as early as the end of next month, a mere three-fifths of the way through the competition.

The former Leeds coach is thought to be heavily interested in the post – the deadline for applications is in 12 days' time – but as he has no experience of operating at Test level, the success of his candidacy would depend on a strong showing over the course of the Six Nations. Things may not get that far. His team could beat both France and Ireland, the two sides most likely to contest the title, in the space of seven days and still not propel him into the top job – a situation that would revive bad memories. Four years ago, Brian Ashton was sacked as head coach despite a thrilling 30-point victory over the Irish in his final game, purely because Twickenham management board members had made a premature and ill-informed decision.

Since Martin Johnson's resignation as manager in late November, the respected South African strategist Nick Mallett has been a hot favourite to fill the vacancy, perhaps with the World Cup-winning All Blacks assistant coach Wayne Smith as his running mate. Their names are certain to feature on a "longlist" of candidates being compiled by a headhunting agency, employed by the RFU to ensure a fair and transparent recruitment process following the embarrassment of last year's palaver over the appointment of a performance director – a shambles that left the governing body with a reputation as the most dysfunctional in British sport.

Quite why the RFU is considering making an early appointment is unclear: apart from anything else, the new chief executive, Ian Ritchie, is still serving his notice at Wimbledon and will not be at his desk until 27 February. The desire to get things sorted well before the three-Test tour of South Africa in June is understandable, but with the Six Nations ending in mid-March, there is no obvious merit in holding Lancaster to an unreasonable deadline – especially as the Twickenham top brass are so delighted with his progress to date.

Stephen Brown, the finance director who has been acting CEO since the departure of the discredited Martyn Thomas before Christmas, said Lancaster had made "a fantastic impression" in driving forward what the RFU calls its "reputational damage rebuild plan" in recent weeks. "If Stuart chooses to apply, he'll come under consideration," he remarked. "The door is not shut, it's open. Yes, it might be a challenging timetable for him, but he was appointed to see the team through the Six Nations, not to be groomed as the full-time coach, although that may be a consequence of what happens on the field. He has to make his own call. It's a major decision for him."

It is not the only major decision on the immediate agenda. An external investigation into the leaking of three post-World Cup reviews – documents containing anonymous criticisms of coaches by players, many of them deeply personal and some driven purely by private resentment – is about to be concluded, but the identity of the culprit will probably remain a mystery. Certainly, those hoping for a Poirot-like revelation of who did what and why are set to be disappointed.

"There is a possibility that even if we have a name, we won't make it public," admitted Brown. "The most likely outcome is that the inquiry will be inconclusive, in which case any naming of an individual would be inappropriate. I am being investigated. So, probably, is Rob [Andrew]. They're investigating everyone who touched the reports. It's extremely unfortunate that someone chose to leak."

Unsurprisingly, given the toxic fall-out from the World Cup, the review system itself is under review. "Trust has been damaged, and we're looking at how it can be repaired," Andrew said. "People's reputations have been damaged too. It's a very difficult process, trying to review something as high-profile as a World Cup. How do we run such a process and make sure it's done in confidence? That's the question."

Happily for the union, the persistent off-field problems in New Zealand, some of which infuriated major business partners, have not led to a drop-off in sponsorship interest. "Some of our clients were surprised at the extent of what happened during the World Cup," admitted Sophie Goldschmidt, the governing body's chief commercial director, "and they clearly want to see that we are learning from it. But many of them have been involved in sport for a long time, have seen the highs and lows and have taken a pragmatic view. We know how important the England team is to everything we're trying to do and we've worked very closely with Stuart on this. He has already spoken about some of the cultural changes he's looking to make and they tie in very closely with the commercial department in terms of what we're seeking to represent."